[BC] Older Cordless phones on 1700

[WFIFeng@aol.com]

In a message dated 07/13/2006 5:58:45 PM Eastern Daylight Time, 
amstereoexp at yahoo.com writes:

> Info on this is sketchy but it seems that the earliest allocation for
>  cordless telephones was 6 AM channels at 1.7 MHz, although I've also heard
>  that 1.7 MHz phones were much more popular in Europe, and these used NBFM
>  (narrow band FM).

Actually, I had worked on several of them, and they were all NBFM. They also 
out out a considerable amount of signal! With a good receiver, it was not 
difficult to hear people's base units from as much as 1/2 a mile away! Of course, 
they were few and far between, back then. It was not difficult to pick up the 
base units on an analog AM radio with just a little tweaking. If the base was 
close enough, the image was clearly audible in the 800 Khz region of the AM 
dial.

>  Anyway, in 1980 the FCC allocated 10 FM channels for
>  cordless phones at 27 MHz, but it seems that the allowed power level was
>  rather high, causing crosstalk problems and inadvertent three-way
>  connections when two neighbors were both using 27 MHz cordless phones.

I seriously doubt that they used 27Mhz. With "freebanders" operating all the 
way from 26 to 28Mhz, (even to this day!) there would be too much interference 
in both directions!

>  So in 1986, the FCC allocated 10 FM channels at 46 and 49 MHz (I think
>  46 MHz is for the base and 49 MHz is for the handset

You are correct, but it was a while before 1986, wasn't it?

>  This was later expanded to 25 channels, in various
>  groups between 43 and 50 MHz. 

I think it was all 49 and 46.

> Then in 1990 came the 900 MHz allocation
>  for cordless phones, 2.4 GHz in 1998, and 5.8 GHz in 2003.  I'm personally
>  a bit confused that the alleged advantage of these higher frequencies is
>  "increased range" -- isn't 5.8 GHz getting up to the point where the walls
>  inside a house will block the signal?

They started using digital spread-spectrum technology, which makes them more 
immune to noise, thus better range than analog. Unfortunately, the 2.4 Ghz 
units don't get along too well with wireless LAN cards in that band.

>  If you really want a vintage cordless phone (either 1.7 or 27 MHz), look
>  out for one where the handset looks like a walkie-talkie and has no
>  keypad.
>  On these old phones the handset was cordless but if you wanted to dial a
>  number you had to walk up to the base.

We had a 1.7 Mhz unit that had a dial in the handset. It was a GE. Worked 
great for many years. It must have been pushing 100mw, easily... possibly more. 
My Dad loved it, because it had good coverage throughout the apartment bldg 
where he was the superintendent... even better after his son tweaked it. ;>

Willie...